Here's one answer, though I can't determine the relative positions of tongue and cheek:

The Christmas cracker was invented, purely by chance, by an English baker called Tom Smith. He took the simple principal of the wrapped sweet or 'bon bon' and added first a love motto then, after much experimenting, a strip of paper impregnated with a compound which would 'crack' when opened. Over the course of time he dropped the sweet, lengthened the wrapper and introduced small novelty gifts.

I guess 2% inspiration and 98% perspiration moves an invention into "purely by chance" territory?